DR. H. DEBUS ON THE CHEMICAL THEORY OF GUNPOWDER. 
543 
0*482 grm. neutral potassic sulphate. Hence, 415 cub. centims. contain 2’23 8 grms. 
of potassium. 
From the solution of the cupric oxide and sulphide in concentrated hydric nitrate, 
1*684 grms. of baric sulphate 
0*231 grm. of sulphur. 
were precipitated; 1*684 grms. 
of baric j 
sulphate contain 
Composition of 
original substance. 
Found by- 
analysis. 
Potassic carbonate . 
„ . 2*219 
2*261 
„ sulphate . 
. . 0*950 
0*953 
„ monosulphide 
. . 0*812{ K =°- 5765 
IS =0*236 
0*7581 
K=0*538 
.S =0*220 
,, hyposulphite 
. . 0*000 
0*103 
S =0*034 
Potassium .... 
. . 2*255 
2*238 
Sulphur in cupric oxide 
. . 0*000 
0*231 
From these experiments it follows, as a general result, that if a solution containing 
potassic sulphate, carbonate and mono- ter- or pentasulpliide of potassium is digested 
with pure cupric oxide, the determination of the potassic carbonate yields in all cases 
a nearly correct result, also for the sulphate an accurate value is obtained in a solution 
which contains the sulphide as monosulphide, but the numbers found for potassic sul¬ 
phides are always incorrect. The potassium hyposulphite is formed by the action of 
cupric oxide upon pentasulpliide of potassium in such quantities that a convenient 
method for the preparation of the salt might be based on the reaction. 
Probably all the potassic hyposulphite, which was found in powder residues by 
Bunsen and Schischkoff’s method of analysis, was formed during the analytical 
operations by the oxidation of potassic sulphide by the oxygen of the cupric oxide. 
At all events, we cannot assume that potassic hyposulphite is one of the products of 
the explosion of gunpowder, because at 225° C. it decomposes, according to Pape, into 
potassic sulphate and pentasulpliide, and because in later experiments, in which zinc 
chloride was used instead of cupric oxide, Noble and Abel found very little potassic 
hyposulphite. We are, therefore, justified in replacing the hyposulphite of the analyses 
of Noble and Abel by its equivalent quantity of potassic sulphide. 
The values found by means of Bunsen and Schischkoff’s method for the potassic 
sulphate would be correct if the powder residues contained only potassic monosulphide. 
But as, according to Linck’s and Noble and Abel’s experiments, they contain one of 
the higher sulphides, it is not improbable that a portion of the sulphate observed has 
been formed during the treatment with cupric oxide from one of the said sulphides, or 
by the decomposition of potassic hyposulphite during the process of analysis. 
The following considerations indicate how this possible error can be corrected :— 
If powder is burnt in the apparatus of Noble and Abel, all the oxygen of the 
decomposed saltpetre is incorporated in the potassic carbonate and sulphate, the 
MDCCCLXX XII. 4 A 
